The dominant L allele is in tight repulsion linkage with the

The dominant L allele is in tight repulsion linkage with the B allele, so it will be impossible to produce the Bb genotype that would express the white phenotype. Normally, it would be expected that 25% of the offspring would be white, but in this case, random deviations from the expected resulted in no white offspring. A testcross is performed on an individual to examine three linked genes. The most frequent phenotypes of the progeny were A bc and aBC, and the least frequent phenotypes were abc and ABC. What was the genotype of the heterozygous individual that is testcrossed with the correct order of the three genes? a. A bc aBC BAC/bac bcA/BCa aBc/AbC bAc/BaC

Solution

The correct answer will be the first one: Abc /aBC

This is because it is stated in the question that Abc and aBC are the most frequent genotypes obtained after three point test cross.

The most frequent are the ones which are parental and least frequent are the double recombinants.

So the parental heterozygotes will be Abc and aBC